1. Field of the invention:
The present invention relates to an improved device for introducing an additive liquid into a carrier liquid which is caused to flow in a main pipe.
2. Brief description of the prior art:
Prior art additive liquid introducing devices of the above type are known which use a difference in pressure produced by a constriction formed in a main pipe through which the carrier liquid is caused to flow. A container is divided in two compartments by a flexible, impermeable. membrane, and has its first compartment connected through a first conduit with the main pipe upstream of the constriction and its second compartment, containing the additive liquid, connected through a second conduit with the main pipe at the constriction or downstream thereof. The container is usually connected to the main pipe through two separate connections, while the second compartment can often be refilled with additive liquid.
In operation, the carrier liquid from the main pipe is transmitted in the first compartment through the first conduit. As the pressure of the carrier liquid upstream of the constriction is higher than that in the constriction or downstream thereof, the carrier liquid in the first compartment applies a pressure on the additive liquid through the flexible membrane. The additive liquid is then introduced in the carrier liquid in the constriction or downstream thereof through the second conduit.
Such prior art additive liquid introducing devices are described, for example, in U.S. Pat. Nos.
______________________________________ 2.865.388 (STERNBERGH) December 23, 1958 2.932.317 (KLOSSE) April 12, 1960 3.166.096 (LANG) January 19, 1965 3.220.435 (ELLINGSON) November 30, 1965 3.720.230 (STOCKSTILL) March 13, 1973 4.210.175 (DANIELS et AL) July 1st, 1980 ______________________________________
As the above listed United States Patents describe two separate connections, often permanent, of the first and second compartments of the container with the main pipe, the use of disposable containers having their second compartment already filled with additive liquid upon purchase would necessitate two time consuming and tedious disconnection-connection operations each time the container is changed. It is the reason why, in the prior art additive liquid introducing devices, the container is often permanent, and is designed for refilling of its second compartment with additive liquid.
An important drawback of the above described prior art additive liquid introducing devices is that they are bulky and relatively expensive. It is therefore expensive to mount some of them, as an example, on different water pipes for introducing different liquid medicaments in these different pipes separately supplying with water different animals in order to achieve different medications on these different animals. Also it is known to mount a prior art introducing device on a pipe supplying with water a plurality of animals; the drawback is that the introduction of a liquid medicament in the water causes supply of the same to all the animals even if only one needs it. As the prior art additive liquid introducing devices are bulky, a plurality of such introducing devices cannot be mounted on a same pipe for simultaneously introducing different additive liquids in the carrier liquid. Moreover, since the prior art devices are often permanently installed, they cannot be easily displaced from one pipe to the other.
Appropriate cares must also be taken when refilling with additive liquid the second compartment of the permanent container. First of all, when different additive liquids have to be successively introduced in the carrier liquid, the second compartment must, in most of the cases, be carefully washed in order to prevent mixing of incompatible additive liquids. When the additive liquids are medicaments, such mixing can produce toxic substances or a medicament with a reduced efficiency.
In the case of a medicament, water or another medicament must often be mixed thereto prior to refilling the second compartment. If such mixing is carried out without precautions by an unskilled person, for example in a non-sterile vessel, the medicament is contaminated.
U.S. Pat. No. 3.392.753 (KLEINMANN) issued on July 16, 1968, discloses an additive liquid introducing device of the above type using a disposable container. Again, the first and second compartments are connected with the main pipe through two different conduits. Replacement of the container therefore requires two different disconnection-connection operations. The container is formed by plastic bottles or jugs having an inner, flexible membrane. These bottles or jugs can be purchased with their second compartment filled with the additive liquid, and are disposed of after use. Such plastic bottles or jugs constitute relatively expensive disposable units.
A further drawback of the prior art additive liquid introducing devices is that each device can introduce in the carrier liquid only one additive liquid at the same time. Consequently, the user is prevented from simultaneously introducing in the carrier liquid different additive liquids which cannot be mixed beforehand, for example medicaments, possibly with different concentrations.